Abstract
ABSTRACT Calcium phosphates, especially hydroxyapatite (HA), are preferred implant materials for implants used to replace bone tissue, like hip-implants, due to their excellent biological properties and bone bonding behaviour. To avoid its poor fatigue properties in loaded applications, HA is supplied as a coating on mechanical strong titanium implant materials. Since plasma spraying, which is nowadays the most widely used technique to apply such coatings, suffers some severe drawbacks, other techniques to apply thin, adherent, and dense coatings are investigated. The aim of this study was to explore the feasibility to apply thin adherent hydroxyapatite layers on titanium substrates by rf magnetron sputter deposition. Especially the effect of variation of different sputter parameters on the properties of the deposited films was investigated. For this purpose deposition power, argon pressure, oxygen pressure and water-vapour pressure was varied during deposition. The films were analysed with ion beam techniques like RBS, ERD, PIXE, XPS and Auger, and with XRD, FTIR, SEM and EDS. To measure the interface strength of the coatings a novel laser spallation technique was used. We were able to get an insight in the parameters which are important for the sputter process, and to obtain dense and thin coatings with a good stoichiometry and an excellent adhesion strength. The results of this research opens the way to the use of these sputter deposited HA coatings in clinical studies.
